Create a singleton all_apex_contributions module type

This will be a container for the the apex_contributions
selected using build flags. This module will be used to query the state of
selected apex contributions instead of a global that can be mutated by
anyone.

It will set a provider containing metadata for source vs prebuilts
selection. To reduce the overhead of a new mutator, this will be done in
the existing `prebuilt_select` mutator.

It will validate that there are no dups (`foo` and `prebuilt_foo` cannot
be both selected)

Bug: 308174923

Test: go test ./android

Change-Id: Ie42999a71f35d70e0e977f5ab07ce451608d9f35

android/prebuilt.go

@@ -435,6 +435,10 @@ func checkInvariantsForSourceAndPrebuilt(ctx BaseModuleContext, s, p Module) {
 
 // PrebuiltSelectModuleMutator marks prebuilts that are used, either overriding source modules or
 // because the source module doesn't exist.  It also disables installing overridden source modules.
+//
+// If the visited module is the metadata module `all_apex_contributions`, it sets a
+// provider containing metadata about whether source or prebuilt of mainline modules should be used.
+// This logic was added here to prevent the overhead of creating a new mutator.
 func PrebuiltSelectModuleMutator(ctx TopDownMutatorContext) {
 	m := ctx.Module()
 	if p := GetEmbeddedPrebuilt(m); p != nil {
@@ -455,6 +459,11 @@ func PrebuiltSelectModuleMutator(ctx TopDownMutatorContext) {
 			}
 		})
 	}
+	// If this is `all_apex_contributions`, set a provider containing
+	// metadata about source vs prebuilts selection
+	if am, ok := m.(*allApexContributions); ok {
+		am.SetPrebuiltSelectionInfoProvider(ctx)
+	}
 }
 
 // PrebuiltPostDepsMutator replaces dependencies on the source module with dependencies on the